[Asterisk-Users] Hook flash hangup instead of hold?

[Barton Hodges]

Currently, if I briefly press the flash hook on my phone, the caller
is placed on hold.  I would like for the channel to hangup if I do
this instead, never placing a caller on hold (I'll be using
call-parking instead).  I disabled threewaycalling that is supposed to
control this, but it doesn't make any difference:

"threewaycalling: If enabled, you can place a call on hold by pressing
a hook flash, whereupon you get a dialrecall tone and can make another
call. Default: no."

Here are the relevent sip.conf statements.  What am I doing wrong?

[channels]
callwaiting             = no
cancallforward          = no
callreturn              = yes
immediate               = no
callwaitingcallerid     = no
threewaycalling         = no
transfer                = no
echocancel              = yes
echocancelwhenbridged   = yes
echotraining            = 800
adsi                    = no
busydetect              = yes
busycount               = 8
callprogress            = no
musiconhold             = random
relaxdtmf               = yes
usedistinctiveringdetection=no
useincomingcalleridonzaptransfer=yes